The present invention relates to a vibrating reed formed of, for example, a crystal, a vibrator having the vibrating reed, an oscillator having the vibrator, and an electronic device having the vibrator.
Conventionally, a tuning-fork-type crystal vibrating reed is constructed as shown in, for example, FIG. 17.
More specifically, a tuning-fork-type crystal vibrating reed 10 comprises a base 11, and two arm sections 12 and 13 formed so as to protrude from the base 11. In these two arm sections 12 and 13, through grooves 12a and 13a are formed.
More specifically, as shown in FIG. 18 which is an A-Axe2x80x2 sectional view of FIG. 17, the arm sections 12 and 13 are formed with the through grooves 12a and 13a. 
In such a tuning-fork-type crystal vibrating reed 10 having the through grooves 12a and 13a in the arm sections 12 and 13, as shown in FIG. 18, excitation electrodes 12c and 13c can be arranged in the inner sides of the through grooves 12a and 13a, respectively.
As a consequence, an electric field is effectively generated between excitation electrodes 12d and between excitation electrodes 13d arranged on the outer sides of the arm sections 12 and 13, respectively, and thus the arm sections 12 and 13 can be vibrated efficiently. Therefore, the vibrating reed becomes a tuning-fork-type crystal vibrating reed 10 having a small vibration loss.
However, when a voltage is applied to such a tuning-fork-type crystal vibrating reed 10 having the through grooves 12a and 13a in order to vibrate the arm sections 12 and 13, since the through grooves 12a and 13a are formed in the arm sections 12 and 13, the rigidity of the entire arm sections 12 and 13 is insufficient, and a problem arises in that the CI value (crystal impedance or equivalent series resistance) increases.
Furthermore, the vibrations of the arm sections 12 and 13 are performed as shown in FIG. 19. Only both end portions of the through grooves 12a and 13a vibrate, and the bending motion of the entire arm sections 12 and 13 will not likely occur.
The vibration is produced in the vicinity of, for example, 16 kHz on both end portions of such through grooves 12a and 13a, and another problem arises in that the frequency is considerably decreased in comparison with 32.768 kHz required by the tuning-fork-type crystal vibrating reed 10.
An object of the present invention is to provide a vibrating reed in which, even if through grooves are provided in vibration arm sections, the frequency is not decreased, and the CI value is not increased, a vibrator having the vibrating reed, an oscillator comprising the vibrator, and an electronic device comprising the vibrator.
According to the present invention, preferably, vibrating reeds from (1) to (10) below are provided.
(1) A vibrating reed comprising: a base; and a vibration arm section formed so as to protrude from this base, wherein a through groove is formed in the vibration arm section, and a rigidity reinforcing section is provided in the through groove.
(2) A vibrating reed, wherein the rigidity reinforcing section is a coupling section formed so as to span the through groove.
(3) A vibrating reed, wherein the through groove has a longer side and a shorter side, and the coupling section is a side bar which is coupled so as to span the longer side.
(4) A vibrating reed, wherein the length of the side bar along the thickness direction is substantially the same as the length of the through groove along the depth direction.
(5) A vibrating reed, wherein the length of the side bar along the thickness direction is shorter than the length of the through groove along the depth direction.
(6) A vibrating reed, wherein the side bar is formed shorter than the length of the through groove along the depth direction by half etching.
(7) A vibrating reed, wherein a plurality of the side bars are arranged.
(8) A vibrating reed, wherein a cut section is formed in the base.
(9) A vibrating reed, wherein the base is provided with a fixation area for fixing the vibrating reed, and the cut section is provided in the base between the fixation area and the vibration arm section.
(10) A vibrating reed, wherein the vibrating reed is a tuning-fork vibrating reed formed of a crystal which oscillates at nearly 32 kHz.